Background and aims – Endemism may be defined according to the time of origin of taxa. Neo-endemics refer to relatively recent species that have not dispersed outside their ancestral areas. In contrast, paleo-endemics refer to species of ancient origins, which are currently geographically restricted but probably were more widespread in the past. Geographically, endemism areas may also be based on the co-occurrence of more than one species. We aimed to qualitatively identify the neo-endemism and paleo-endemism of endemic Cactaceae of the Tehuacán-Cuicatlán Valley, as well as to quantitatively assess paleo- and neo-endemics areas. Material and methods – Using a dated molecular phylogeny of endemic Cactaceae, we defined paleo- and neo-endemics using an arbitrary boundary of 2.6 million years ago; we also assessed the significance of concentrations of these species using a categorical analysis of paleo- and neo-endemism. Key results – Our results showed that most endemic Cactaceae in the Tehuacán-Cuicatlán Valley arose throughout the Pleistocene, while categorical analysis indicated localised mixed- and super-endemism (including both paleo- and neo-endemics) areas. Conclusion – We suggest that paleo- and neo-endemics, as well as localised mixed-endemism areas, may have originated due to a probable high climatic stability in the Tehuacán-Cuicatlán Valley, which in addition to topographically rugged and ecologically complex zones (e.g. ecotones, isolated habitat patches) may have allowed it to function as a refuge throughout Pleistocene climatic changes, mainly promoting the speciation of neo-endemics, as well as the persistence of relatively few paleo-endemics.

Mexican dry environments are widespread and characterized by a rich flora and fauna in terms of both overall species diversity and endemism, but the factors that have shaped this diversity remain unclear. In this study, we evaluated hypotheses concerning the biogeographical origin and evolutionary history of Florestina (Asteraceae) in Mexican dry environments. For this, we generated a time-calibrated phylogenetic tree from the nuclear non-coding external and and internal transcribed spacers (ETS, ITS), using the program BEAST. Based on this phylogenetic tree, we employed the package BioGeoBEARS to infer the historical biogeography of the genus, comparing different biogeographical models and estimating the ancestral range probabilities. Our time-calibrated phylogenetic tree suggested that the genus Florestina diverged during the early Pliocene c. 5.2 Mya and diversification continued throughout the Pleistocene. Furthermore, results suggest that the biogeographical origin of the Hymenothrix/Palafoxia/Florestina clade was in Nearctic regions, not in Neotropical regions as previously suggested. We hypothesize that the ancestor of Florestina became disjunct and isolated in tropical dry forests of southern Mexico from Palafoxia after the rifting of the Baja California peninsula from the Mexican mainland.

Twenty-one years have elapsed of the 21st Century and within the framework of the celebration of the 100th volume of Botanical Sciences, it is relevant to assess the progress of the research on conservation and on the activities undertaken for protecting the plants of Mexico, including the complementary in situ and ex situ approaches. By means of a systematic search of scientific articles related to the conservation of the Mexican flora on the Web of Science database, for the 2000–2021 period, we identified different scientific inputs, all showing specific objectives for undertaking conservation activities. The publications that resulted from this search were classified into six categories: (a) Regions and Ecoregions; (b) Communities or Ecosystems; (c) Taxonomic Groups; (d) Species and Populations; (e) Botanical Gardens; and (f) Seed Banks. For these categories, the results are presented under the headings “in situ conservation” and “ex situ conservation.” Additionally, we assessed by a random examination, the bibliography used to support touristic development projects. The results show that, despite the wide temporal range considered in this review, and even though there is a vast number of publications related to the characterization of the Mexican biodiversity, the production of scientific work oriented to the development of plant conservation strategies and activities is still scarce. Also evident is the lack of connection and communication among researchers of different disciplines, highlighting the disciplinary or multidisciplinary activities that they undertake. Finally, ten conclusions are presented, and some future research activities are suggested for conserving the Mexican flora.

Asteraceae species diversity is high in the xerophytic scrub of the Ecological Reserve of the Pedregal of San Angel (REPSA), located in the southern part of the Basin of the Valley of Mexico. Here we determined whether the frequency of polyploidy is high in the reserve, given the enhanced ability of polyploids to colonize new habitats. In addition, we compared the frequency of polyploidy in Asteraceae in the reserve with the frequency in three oceanic archipelagos and two continental areas in Mexico. This was done to see how the ‘virtual’ island of the open lava flow in the reserve compares with volcanic islands at different distances from source areas. Chromosome numbers for 75 species of Asteraceae were obtained from published literature. Based on the possession of three or more basic chromosome sets in a nucleus, 33% were polyploids. If taxa with haploid chromosome numbers of n ≥ 14 or n ≥ 11 were considered to be polyploids, the proportion of polyploids rose to 57 and 75%, respectively. When using a phylogenetic approach, the highest percentage of polyploids (84%) was obtained and it could be inferred whether they are palaeo- or neopolyploids; thus, we consider that this criterion better reflects the events of polyploidy in Asteraceae. A high frequency of polyploid species in Asteraceae in REPSA suggests that polyploids may have contributed to the species diversity and the vegetation structure of the xerophytic scrub of this reserve.